The amount of data stored, collected, and used by various onboard computer systems of a typical aircraft is growing at a rapid pace. For example, the onboard systems utilize data for various cabin systems, avionics systems, and inflight entertainment systems. Operational and maintenance data including aircraft condition monitoring function (ACMF) and engine performance data may be generated during the flight and needed to be shared with other systems. Airlines are generally responsible for updating the data and software configuration items on their aircraft (for flight operations and passenger entertainment) and timely downloading from the aircraft (pertaining to maintenance and system performance logs). For example, data collected during one or more previous flights may need to be transmitted to an external network used by an airline. All these activities require fast and secure data transmissions between aircraft and external networks while the aircraft are on the ground, for example, at an airport gate in between flights. While data transmissions may be performed using a variety of airport Wi-Fi or cellular communication channels, availability of these channels may be limited at many airports. Furthermore, the security of these channels may not be adequate for some data types and locations.